Aluminum alloy brazing sheet and brazing method

Abstract

A brazing method of performing brazing on an aluminum alloy brazing sheet by increasing a temperature from 200° C. to a brazing temperature in an inert gas atmosphere with a dew point controlled to −20° C. or lower, thereafter increasing the temperature in an inert gas atmosphere with a dew point controlled to −40° C. or lower and an oxygen concentration controlled to 100 ppm or lower, and performing brazing heating in an inert gas atmosphere at a temperature of 580° C. to 615° C. without using flux. The aluminum alloy brazing sheet has a structure in which one or both of a core material and a brazing material includes any one or two or more types of X atoms (X is Mg, Li, Be, Ca, Ce, La, Y, and Zr), and oxide particles including the X atoms and having a volume change ratio of 0.99 or lower are formed on a surface thereof.

1 . An aluminum alloy brazing sheet used for brazing in an inert gas atmosphere without using flux, the aluminum alloy brazing sheet comprising:
 a core material of aluminum or aluminum alloy; and   a brazing material of aluminum alloy including Si of 4.0 mass % to 13.0 mass % and cladding one side surface or both side surfaces of the core material, wherein   one or both of the core material and the brazing material includes any one or two or more types of X atoms (X is Mg, Li, Be, Ca, Ce, La, Y, and Zr),   when only the core material includes the X atoms, a content of each of the X atoms in the core material is 0.01 mass % to 2.0 mass %,   when only the brazing material includes the X atoms, a content of each of the X atoms in the brazing material is 0.001 mass % to 0.03 mass %,   when both the core material and the brazing material include the X atoms, a content of each of the X atoms in the core material is 0.01 mass % to 2.0 mass %, and a content of each of the X atoms in the brazing material is 0.001 mass % to 0.03 mass %, and   the aluminum alloy brazing sheet is a brazing sheet in which oxide particles including the X atoms and having a volume change ratio of 0.99 or lower with respect to an oxide film before brazing heating are formed on a surface thereof, by brazing heating.   
     
     
         2 . The aluminum alloy brazing sheet according to  claim 1 , wherein the core material is aluminum alloy including:
 the X atoms in which a content of each type of the X atoms is 2.0 mass % or lower; and   any one or two or more types of Mn of 1.8 mass % or lower, Si of 1.2 mass % or lower, Fe of 1.0 mass % or lower, Cu of 1.5 mass % or lower, Zn of 3.0 mass % or lower, and Ti of 0.2 mass % or lower, with the balance being Al and inevitable impurities.   
     
     
         3 . The aluminum alloy brazing sheet according to  claim 1 , wherein the brazing material is aluminum alloy including:
 Si of 4.0 mass % to 13.0 mass %; and   the X atoms in which a content of each type of the X atoms is 0.03 mass % or lower, with the balance being Al and inevitable impurities.   
     
     
         4 . The aluminum alloy brazing sheet according to  claim 1 , wherein the brazing material is aluminum alloy further including Bi of 0.004 mass % to 0.2 mass %. 
     
     
         5 . The aluminum alloy brazing sheet according to  claim 1 , wherein the brazing material dads one side surface of the aluminum alloy brazing sheet, a sacrificial anode material dads the other surface of the aluminum alloy brazing sheet, and the sacrificial anode material is formed of aluminum alloy including Zn of 0.9 mass % to 6.0 mass % with the balance being Al and inevitable impurities. 
     
     
         6 . A brazing method of performing brazing by performing brazing heating on an aluminum alloy brazing sheet in an inert gas atmosphere at a temperature of 580° C. to 615° C. without using flux, wherein
 the aluminum alloy brazing sheet is the aluminum alloy brazing sheet according to  claim 1 , 
 increase in temperature from 200° C. to a brazing temperature is performed by increasing the temperature from 200° C. to a condition switching temperature in an inert gas atmosphere with a dew point controlled to −20° C. or lower, and increasing the temperature from the condition switching temperature to the brazing temperature in an inert gas atmosphere with a dew point controlled to −40° C. or lower and an oxygen concentration controlled to 100 ppm or lower, and 
 the condition switching temperature is 450° C. or lower. 
 
     
     
         7 . The brazing method according to  claim 6 , wherein a heating time of the brazing heating is 1 minute to 15 minutes.